The Fourth Age began after Sauron was finally defeated, when his Ruling Ring was destroyed, and all the Elves but one left Middle-earth for the Uttermost West.The Fourth Age is also marked by the crowning of the next king of Gondor. Aragorn Son Of Arathorn. And the next queen of Gondor. Arwen daughter of Elrond.

Tolkien's writing does not provide information on more than the first few centuries of this age, so it is not known when it ended, if it ever did.

This age was (presumably) marked by the recovery of the Númenorean kingdoms in exile (Arnor and Gondor), the final ascent of Men and the total wane of the Elves.

Tolkien said that he thought the distance between the end of the Third Age and the 20th century A.D. was about 6000 years, and that in 1958 it should have been around the end of the Fifth Age if the Fourth and Fifth Ages were about the same length as the Second and Third Ages. He said, however, in a letter written in 1958 that he believed the Ages had quickened and that it was about the end of the Sixth Age/beginning of the Seventh.

For a complete list of events during the Fourth Age, see the Timeline.